Thermostatically controlled device



Aug. 23, 1938. J. A. SPENCER THERMOSTATICALLY coNTRoLLED DEVICE originai Filed' April 9, 1954 2 sheets-sheet 1 FIG. 3.

DISPLACEMENT .lll NQkOm Aug. 23, 1938.

J. A. SPENCER Re. 20,835

v THERIIOSTATICALLY CONTROLLED DEVICE Original Filed April 9, 1934 fill 2 Sheets-Sheet 2 Reissues] Aug. 23, 1938 UNITED STATES PATENT oFFl-CE THERMOSTATICALLY CONTROLLED DEVICE John A,` Spencer, Newtonville, Mass.,1a'ssignor, by

mesne assignments, to Metals da Controls Corporation, Attleboro, Mass., a

Massachusetts corporation of '1 Claims.

devices such as valves and electric switches havv ing a manual reset mechanism;

Among the severalobjec'ts of the invention may be noted the provision of a thermostatically controlled device of the class described vwhich periorms an opening or closing function automatically upon the attainment of a predetermined temperature condition but which is incapable of performing the respective reverse function without manual actuation; the provision of a device of the class described which performs its automatic function with a snap-action without the use of latches, pivot points, or toggles thus operating with less friction and hence being more accurate in its response to temperature change;

and the provision of a device of thc class del scribed which is relatively simple in construction and operation. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described', and the scope of the application of which will be indicated in the following claims.

In th accompanying drawings, in which are illustrated several of various possible. embodiments of the invention,

Fig. 1 is a longitudinal cross-section of a valve embodyingthe present invention;

Fig. 2 is a graphical presentation showing certain force-displacement characteristics of an actuating element`of the valve of Fig. 1;

Fig. 3 is a lateral cross-section taken substantially along line 3-3 of Fig. 1;

Fig. 4 is an enlarged fragmentary view of a portion of Fig. 1; f

Fig. 5 is a longitudinal cross-section of an electric switch embodying the present invention;

and,

Fig. 6 is a lateral cross-section taken substantially along line 6-'-6 of Fig. v6.

Similar reference characters indicate corresponding parts vthroughout the several views of the drawings.

The present invention applies to control devices of all types wherein a. response is to be made to temperature variations. Principal among such control devices are valves and electric switches, which accordingly constitute the more usual controlled or actuated elements falling within the scope of the invention. The invention, in principle, applies equally well to these and other types of control devices, but for purposes of description, the application of the invention to devices of those two characters will sufiice. Y

Referring now more particularly to Fig. 1, nu-

ICl. S-117.1)

meral I indicates a valve body having an inlet 3 and an outletV 5 respectively. The body I includes an internal chamber, which is divided by a customary partition 6 into an inlet chamber 1 and an outlet chamber 9. The partition 6 includes an openlng'I I, which provides a valve seat I3, in the usual manner. v

, Extending in one direction from the valve casing I at right angles to the plane of the opening is a cylindrical housing member I5, which inwardly terminates in a bearing portion I6. The member I5 is closed at its outer end by a threaded plug I1. The plug I1 has a central threaded opening to receive the threaded stem I9 of a ilexible bellows 2|. The relative position of the bellows 2| inthe cylindrical member I5 may be adjusted by'threading the stem I9 into and out of the plug I1. bellows in positionV once it is established.

Sealed tothe outer end of the stem I9 is a. so-called capillary metallic tube 23, which is suiciently flexible to permit of its being bent, without breaking, during installation of the device. To the other end of the tube 23 is ailxed a bulb 25. The bulb 25, tube 23, stem -IS and bellows 2| are all ysealed together in a closed arrangement, so that no leakage of a fluid in the system may take place.

The bearing portion I6 slidably receives a stem 21 to which is affixed valve closure element or disc 29. The disc 29 is adapted to seat upon the valve seat I3, in order to place the valve in closed condition so that communication between inlet 3 and outlet 5 is cut oil. The opposite end of the valve stem 21 abuts the inner end 3| of the bellows 2|.

On the opposite side of the valve casing is provided a threaded opening 33 which is coaxial with the cylindrical housing I5. Into the opening 33 fits a threaded cap or plug 35, which outwardly terminates in a bearing portion 31. The bearing portion 31 includes a central opening 39 through which slides a stem 4|. To the outer end of the stem 4| is threaded a manually operative knob 43. The inner end of the stem 4| (see Fig. 5) is drilled and threaded to receive an adjustable threaded extension 45 which is unattached to but abuts against the valve closure element 29 and is locked after adjustment by a lock nut 46. The extension 45 has a hexagonal portion 50 for convenience in adjusting and has a spherical end surface 52 for abutting againstthe valve closure element 29. The valve closure element 29 lhas a corresponding spherical depression 54.

The cap 35 is inwardly shaped to provide a cylindrical opening 41, which has an annular shoulder 49 near its bottom. Seated peripherally upon the shoulder 49 is a snap-acting corrugated disc 5|, which comprises in effect an actuator for A lock nut 22 holds the the valve assembly. 'Ihe disc 5| is preferably made in accordance with the teachings of my copending patent application, Serial No. 653,702.

flied January 26, 1933, for Snap acting device,

now Patent No. 1,972,172, granted September 4, 1934, It comprises (see also Fig. 3) a disc of resilient metal, such as spring brass, steel or the like, which is provided with a relatively large number of radial corrugations 53, a central opening 55, and a i'lat uncorrugated rim portion 51. It is the ilat rim portion 51 that seats upon the shoulder 49. Ihe disc 5| is initially formed in such manner that its general shape is slightly conical in one direction. As a result of the initial shaping of the disc, it may be over-centered by applying a force to occupy a conformation of conicity in the opposite direction.

The disc 5| is distinctive in its characteristic curve for the applied force against the displacement, which is shown in Fig. 2. While this curve is described in more detail in my said patent, No. 1,972,172, it will also be described herein, but only to the extent necessary to enable a full understanding of the present invention.

Considering zero displacement to represent the conformation of the disc as it is initially shaped, and considering the distance through which the central portion of the disc travels in over-centering as a finite positive displacement, the curve indicated by numeral 59 in Fig. 2 represents the characteristic displacement to be had for increasing applied forces. Following the curve 59 from the origin, it will be noted that at rst relatively little displacement is obtained as the applied over-centering force .is increased until said force builds up to a value Il. However, the instant after the force fl has been achieved, displacement will increase rapidly even under an applied force less than the value of fl. That is to say,

40 in the portion of the curve 59 immediatelybeyond its rst crest, the displacement increases with a decreasing applied force, which is, of course, contrary to the ordinary type of spring, which obeys Hookes law. Thus, the force may 4| be gradually decreased along values determined by the curve 59, with the displacement none the less increasing. This action continues until the force has diminished to a value f2. Thereafter, according to the curve 59, it is again necessary to increase the applied force in order to procure an increased displacement. The portion of the displacement to the right of f2 on the curve is not used, the disc being stopped from being displaced further by the inside surface of the cap Ierable degree of displacement.

35, If the force fl is applied by a resilient spring force fl has been reached, the applied force may be diminished and the displacement will still be increased, The force f2 will be suflicient to hold the disc in a position of comparatively great displacement, although a larger force fl has been necessary to get the disc to such a displacement. For purposes of brevity, the Fig..1 position of the disc with the displacement less than that corresponding to a force f| will hereinafter be termed the position of absolute stability of the disc, and the position oi the disc in its displaced position under the force f2 will be called the position of comparative stability. The peculiar application of this type of disc in the valve of the present invention will be made apparent hereinafter.

Returning to Fig. 1, it will be seen that a nut or collar 6| is threaded on the stem 4| in a position to be abutted by the inner periphery of the disc 5|. The nut 6|, also provides one abutment for a exible diaphragm 63. The diaphragm 63 is clamped against the nut 6| by a second nut 65 so that a leak-proof joint between the diaphragm 63 and the stem 4| is afforded. The outer periphery of the diaphragm 63 is tightly clamped against the inner surface of the cap by means .of a rim or plug member 61, which is forced into its position. Thus, leakage through the mechanism enclosed within the cap 35 is prevented.

In order to prevent the stern 4I from turning in the bearing 31, the stem 4| is provided with a longitudinal groove 69, into which ts a pin or key 1| radially disposed in the bearing portion 31. Groove 69 permits longitudinal motion of the stem 4I but prohibits rotative motion thereof.

'I'he nuts 45, 6|, and 65 are initially so adjusted that the resilient force of the disc 5I, when` in its position of absolute stability, is brought to bear upon the stem 4| in such manner as to tightly seat the valve closure element 29 upon the valve seat I3. The spring reaction of the `disc 5I is between the nut 6| and the shoulder 49.

The operation of the valve as thus described is as follows:

The system comprising the bellows 2| and bulb 25 is filled with a iluid or gas or the like which undergoes considerable volume change upon change of temperature. The choice of the fluid or gas to be used depends upon the range of temperature in which the device is to be used. Argon, for example, has been found best in the present instance because of the high temperature at which it is desired to operate the bulb'. Argon is an inert gas even at high temperatures and the walls of the container are less permeable to it than to other inert gases. Under what will hereinafter be termed cold conditions, the vol-- ume of the fluid is such that the end 3| of the bellows 2| exerts a force substantially less than f2 upon the stem 21. This adjustment may be e'ected by loosening the nut 22 and rotating the threaded stem I I to regulate the longitudinal position of the bellows 2| in the cylindrical housing I5, and thereafter retightening the nut 22.

If the bulb 25 is now heated, as by a pilot flame indicated by numeral 13, the fluid in the system will expand and tend to move the end 3| of the bellows 2| into the valve assembly in order to relieve the increased volume due to the heat. 'I'he adjustment of the bellows 2| in the housing I5, however, is so arranged that under normal temperature conditions the inward force of the bellows 2| is never permitted to build up to the value fl for the particular disc 5| used, although a force slightly exceeding f2 is reached.

If, now, the bulb 25 is in its heated condition, and the knob 43 is manually grasped and pulled A(to the left in Fig. l), the manual force will overcenter the disc 5| to its position of comparative stability, and the force supplied by the pressure of the bellows 3| will be suicient to hold said disc 5| in its position of comparative stability and hence hold the valve open. When, now, the pilot flame 13 goes out, the fluid in the bulb 25 cools and the pressure of the bellows 2| is relieved. This means that the force supplied by the bellows 2| decreases below the value f2. 'I'herefore the disc 5| will at once return to its position of absolute stability, at the same time closing the valve. Subsequent heating of the bulb 25, as by reignition of the burner 13, will not provide sumcient force again to open the valve by itself, butmanual pulling of the knob 43 is necessary.

A particular advantage of a valve constructed in this manner is the promptness with which it may be said to go oil" immediately after the flame 13 has been extinguished. It will be, understood that the action of the fluid in the bulb is essentially a thermostatic one, that is, control is effected in accordance with the temperature of the fluid. Now, with all snap-acting thermostatic devices there is present what is known as an operating differential. That is to say, on decreasing temperature, an action will be' performed when a temperature, say 100 is achieved, while on increasing temperature with the same device, a contrary action will be achieved with a temperature of say 150". The difference between these values (e. g. 50) represents what is spoken of as the operating diierential of the thermostat. Now, in connection with safety devices of the type herein concerned, it is desirable that the operating tempera-ture differential be reduced to an absolute minimum, for it is advantageous, of course, to shut off the ilow of gas immediately upon extinguishment of the pilot burner. The valve described is so designed that thermostatic operation is had only upon the lower value of the two limit figures going to make a temperature differential. 'I'he upper value is, for practical purposes, beyond reach, and is replaced by the manual actuation ofthe valve to open position. Thus. the valve as described may be adjusted so that the normal temperature induced by the pilot llame 13 is :lust suiilcient to provide a force at the bellows 2| which very slightly exceeds the value l2 for the particular disc 5| employed. Then, almost instantaneously after the flame 13 is extinguished the slight drop of temperature in the ybulb 25 is suillcient to cause the pressure in the bellows 2| to decrease below the value l2 and hence cause the valve to close.

n is desirable that the disc sl be so mountedthat its motion in the valve-seating direction is limited to the extent that the maximum force f I presses the valve closure element 29 against its seat I3 thus providing a good pressure for holding the valve closed.

The invention, when applied to an electric switch as the controlled or actuated element, operates upon the same basic principles. For example. Figures 5 and 6 show the adaptation of the invention to an electric switch for use in the same type of circuits as the valve embodiments described. The embodiment shown in Figures 5 and 6 is in many respects similar to the valve embodiment of Fig. l. insofar as the thermal actuating element is concerned.

Referring to Fig. 5, it willlie seen that a body "member indicated generally by numeral I2I is provided, comprising a cylindrical bellows housing I5 joined by two arms |23 to a circular base portion |25. The housing I5. which is similar in all respects to the housing I5 in Fig. l, contains the bellows 2|, and is closed by a plug or cap I1, into which the stem I9 of the bellows 2| is threaded. Other details are like the Fig. 1 embodiment described.

The circular base portion |25 has in the outer face thereof, a circular depression |21. The edge of the depression |21 is provided with an annular shoulder |29, against which rests the flat rim 51 of the radially corrugated disc 5| (identical, in itself, to the discs of the valve embodiment'described). Fitted against the outer face of the base |25, and secured in place by screws |3|, is a plug or nipple |4| having a polygonal head |43 A for turning it. A lock nut |45 secures the plug |4| in position once it has been adjusted.

Passing through a central bearing hole |41 in the block |33, the central hole 55 of the disc 5|, and the hollow plug |4|, is a main stem |49 similar, in many respects, to the stern 21 of the Fig. l embodiment. 'Ihe stem |49 has a forward portion |5I of reduced diameter, and is threaded at its end to receive the manual control knob 43. A threaded portion |53 receives nuts |55, the purpose of which will be made clear hereinafter. A smooth portion |51 slides in the hole |41, and passes through the central hole 55 of the disc 5|. The remainder of the stem |49 is threaded as at numeral |59, and carries a washer |6I held tight against the shoulder formed by the reduction in size from smooth portion |51, by a nut |63. The washer |6I forms an abutment for the edges of disc 5| whereby it is operatively connected to the stem |49. The adjustable nipple |4|, against which the other side of washer |6| abuts, will thus be seen to comprise a movement-limiting adjustable stop for the disc 5|, performing in this respect an analogous function to that of the adjustable screw 45 of the Fig. l embodiment.

At the extreme end of the stem |49 is provided a long nut |65, which is locked against movement by a nut |61. The nut |65 extends beyond the end of the stem |49 for adjustment and extends through a hole |69 in the end-wall |23 and is in position to be abutted by,and hence susceptible to the movement of, the bellows 2|.

The electrical elements of the switch are shown more clearly in Fig. 6, They comprise a pair of terminal pieces |1| and |13 which are mounted upon the insulation block |33 by rivets |15. Each terminal piece has an upstanding, facing projection |16 and |11, respectively, a gap being left therebetween. The terminal pieces likewise have` connecting screws |19 and |8I, respectively, by which electrical connections are made to the switch. Mounted on a projection |83 from the block |33, by means of a screw |95, is a strip |91 ofy resilient metal, the free end of which carries a universally-jointed contact button |99, and which is provided with a hole |9| to receive the stem |49. The lock nuts bear against outer side of strip or lever |81. The contact button '|99 is of such size, and so positioned, as to move into and out of contact with the terminal-piece projections |15 and |11, whereby the switch makes and breaks connections.

A projection |93 from the base portion |25 carries a bushing |95 made of insulating material,

through which bushing are passed the wires shaped cover |01 (with a notch to accommodate the projections |93) tits on the casing lli and completely encloses the working parts of the switch. Only the manual knob 43 passes through the cover Il'l. Y

'Ihe operation of this embodiment of the invention is similar to that of the embodiment heretofore described. with the exception that electrical switching elements, in place of valve elements, are the primary actuated means. Normal position, with the switch disconnected, is shown in the drawings, and the actuating disc 5| is then in its convex-to-the-right position. This is also the position of absolute stability of the disc. The actual displacement of the disc tothe right (and hence its operating resistance) is controlled by adjusting the position of the plug Ill.

When, now, the knob 43 is grasped and pulled to the left (Fig. 5), the disc 51 is overcentered to its position of comparative stability, in which position it is held if the pressure oi'.` thebellows 2| (and hence the vexternal temperature) is high enough to exceed the value f2 of the chart, Fig. 2. If the temperature drops sufficiently, the pressure oi' the bellows 2| decreases below the value f2, and thereupon the disc snaps back to its posiA tion of absolute stability. When the disc is in its position of absolute stability, the switch is open, button IBS being out of bridging relation with respect to the projections |15 and |11. When, however, the disc 5| is in its position of comparative stability, the contact button |89 bridges or connects the projections |15 and Ill and connections are thus made. Automatic opening of the switch takes place in the same manner, and for the same reason, as the automatic closing of the valves hereinbefore described. It will readily be apparent, however, that the order of the positions of the disc with relation to the position or condition of the contact elements might be reversed, s'hould the occasion demand.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As,many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall b'e interpreted as ulustranve and not in a. 11maing sense.

I claim:

1. A temperature controlled device comprising actuated control means, actuating means for said control means, said actuating means comprising a radlally`corrugated snap-acting resilient metal disc having a position of absolute stability and a position of comparative stability, and being characterized in that the force required to initiate movement of said disc from its position of absolute stability to its position l.of comparative stability is greater than the force required to maintain said disc in its position of comparative stability, thermally responsive means comprising a bulb and bellows unit positioned to react upon said actuating means and, under proper thermal conditions, to supply the force necessary to maintain said disc in its position of comparative stability, said thermally responsive means, however, being incapable, under normal temperature variations, of supplying a force suiliciently great to initiate movement of the disc from'itsv position of absolute stability to its position of comao,sss

parative stability, and manually operable means for supplying sumcient force tomove said disc from its position oi' absolute stability to its posi tion oi' comparative stability. 2. A temperature controlled device as set forth in claim 1 in which the actuated control means comprises a valve closure element, and in which the actuating means operates on one side of said element, while the thermally responsive means operates on the other side of said element. 3. A temperature controlled device as set forth in claim 1 in which the actuatedcontrol means comprises a valve closure element, and in which the actuating means operates on one side of said element, while the thermally `responsive means operates on the other side of said element, both said actuating means and said thermally responsive means being free of any permanent attachment to said valve closure element.

4. A temperature controlled device as set forth in claim l in which the actuated control means comprises a valve closure element, said element having a stem extending from one side thereof, bearing means for said stem, said thermally responsive means operating on the remote end of said stern, while said actuating means operates on the opposite face of said element.

5. A control valve comprising a valve housing having inlet and outlet openings with a valve seat therebetween, a closure member threading into said housing above said seat and having a cupshaped recess in the inner face thereof, a valve member in said housing cooperating with said valve seat and having a valve stem extending from said housing oppositely of said closure member, a resetting stem reciprocable in said closure member and having means at its lower end engaging said valve member, spring means in said recess biasing said resetting stem toward valve closing position and sealed from the interior of said housing, and means on said stern operative torender saidvspring means inoperative.

6. A control valve comprising a. valve housing having a. valve seat therein, a valve member cooperating with said seat and having a valve stem extending outwardly of said housing, a closuremember secured in said housing above said seat and carrying resetting means normally urging said valve member to closed position, said housing having an integral valve stem guide provided with an enlarged outwardly extending cylindrical poru tion encircling said stem, a pressure responsive member acting on the .outer end of said stem within said cylindrical portion, and adjusting means closing the outer end of said cylindrical portion and engaging a portion of said pressure responsive member.

7. In combination, a valve housing, a valve member in said housing having a depending valve stem, expansive means at the end of said stem operable to react upon said stem in accordance with temperature variations at remotely disposed pressure developing means, a. closure member for said housing disposed over said valve, a reset stem carried by said closure member and projecting therefrom, means at the inner end of said reset stem bearing against the upper surface of said valve member, spring disc means disposed about said reset stem within said closure member and normally urging said reset. stem downwardly l. 

